Joint structure for pivoted tools



April 15, 1952 E. BALDERSTONE JOINT STRUCTURE FOR PIVOTED TOOLS FiledDec. 29, ,1945

FIG I- FIG: 2

3twentor Edward fiaklegwion e Gttorneg Patented Apr. 15, 1952 2,592,641"JOINT STRUCTURE FOR. rrvo'rnn TOOLS Edward Balderstone, Oakford, Pa.,assignor to The S. S. White Dental Manufacturing Company, a corporationof Pennsylvania Application December 29, 1945, Serial No. 637,861

My invention relates particularly to that class of forceps that'areadapted tobe employed by dental practitioners in the extraction ofteeth, and is especially directed to the pivotal joint structureconnecting the opposed jaw members of such implements.

It is well known that several types of pivotal joints have been employedin the manufacture of such forceps or pliers, including the box joint,the knuckle joint and the so called scissor type joint. The box jointhas heretofore been preferred for dental and surgical purposes for-thereason that it is deemed to have superior strength and that it wassusceptible of being finished to a rounded or oval cross section withoutintroducing any objectionable characteristics. It is obvious that theoval joint structure is, superior because of its freedom from projectingedges its minimum bulk and its consequent smoothness to the feel of thehand of the operator.

It has been known that properly designed forfixed position such, forinstance, as when normally closed.

The principal objects ofmy invention are to provide scissors type plierswith the joint structure having a rounded or oval configuration, and

having a-pintle whose head terminates short of the outer oval surface ofthe relatively movable jaw member.

Other objects of my invention are to provide forceps of the typecontemplated in which its pintle is rigidly engaged with one of therelatively movable jaw members, while its retaining head rotatablyterminates within the other of said jaw members, and is covered by aplate or cap formed in integral relation with said jaw member andconforming with the oval or rounded surface of said jaw member in whichsaid head is disposed.

Further objects of my invention are to provide forceps or likeimplements having relatively movable jaw members joined by a pintle, oneof said jaw members being provided with a cylindrical orifice having aledge affording a seat, the other of said jaw members having a conoidalorifice provided with indentations, a pintle extended through saidorifices and having a head rotatably 2 Claims. (01. 32-452) engaged withsaid seat while its free ail-east] is upset or riveted tointegrally'engage the indented walls of said conoidal orifice.

Specifically stated, the form of my invention as hereinafter describedcomprises forceps having relatively movable jaw members each includingahandle and a beak, and being joined pivotally together by a pintle andaffording a jointed region whose outer surfaces are rounded, each jawmember of said pliers being provided with a relatively registeringaperture, one having a conoidal recess which includes indentations, andthe other having a cylindricalrecess affording a' circular seat and acounter recessarranged to receive .a plate or cap, a pintle initiallycomprising a cyflindrical shank which is arranged tobeextended throughsaid apertures and an enlarged head fitted in said cylindrical recesswhile ;the free end region of said shank is upset to fill said. conoidalrecess, and a cap initially having an upper conical surface and a lowerre-entrant My invention'also includes all of the jva rious:

novel features of construction and arrangement as hereinafter moredefinitely specified.

In'the accompanying drawings, Figure 11 13TH) plan view of a pair ofdental forceps=conveniently-embodying myinventi'on; Fig. 2 isafsideelevational view of the forceps illustrated in :Fig; 1; Fig. '3 isanenlargedtransverse vertical ','sec.

tional view taken through the joint of the pliers;

in the axial plane of the pintle, as indicated by the section line 3- -3in Fig. 1; Fig. 4' is a perspective view illustrating the initialformation of the headed pintle which is shown expanded in Fig. 3; Fig. 5is a plan view illustrating the initial formation of the pintle headcover or cap shown in Figs. 1 and 3; Fig. 6 is a transverse verticalsectional view of the cap shown in Fig. 5, taken axially therethrough onthe line 6-$ in said Fig. 5; and Fig. 7 is a fragmentary inverted planview of the under jaw member of the forceps showing the indentations inthe conical wall of the pivotal aperture extending therethrough.

In said figures the forceps illustrated comprise the relatively movablejaw members I and 2 pivotally joined together to relatively rock aboutthe axis of the pintle 3. The upper jaw member I, with reference to theillustrations, includes the handle 4 and the beak 5, and the lower jawmember 2 similarly includes the handle 6 and the relatively opposed beak1.

As illustrated in Fig. 3, the jaw members i and 2 are respectivelyprovidedwith the relatively alined apertures 8 and 9 through which theshank of the pintle 3 extends. Said pintle is initially formed as shownin perspective in Fig. 4 and is provided with the head H).

As shown in Fig. 3, the aperture 8 concentrically joins the cylindricalrecess [I which affords the ledge or seat 12 against which the undersurface of the pintle head ill rests, so that the upper surface of saidpintle head It is disposed. well within the body of the upper jaw memberI.

Again referring to Fig. 3, the upper jaw member I is also provided withthe counter recess I3 preferably having the retaining undercut or groove14 into which the closure cap [5, initially formed as shown in Figs. and6, may be forced and thus caused to assume the form illustrated in Fig.3 to provide a convenient closure integralwith the jaw member I, for thehead it! of the pintle 3.

Referring further to Fig. 3, the pintle aperture 9 in the lowerjaw'member 2, concentrically joins the conoidal recess 15 which, asillustrated in Fig. 7, includes a circularly arranged series of angularindentations l1 disposed in relatively angular axial planes in theconical wall of said recess I9 and which may preferably extend into thecylindrical wall of said pintle aperture 9, as shown in dotted lines inFig. 3.

It will be obvious that the lower region of the shank of the pintle 3,shown in Fig. 4, will, when entered through the apertures Band 9 and subjected to high pressure or riveting action, con:

form to the conoidal recess I6 and its indentations i! into integralrelation with the lower jaw member 2. a

It has been found in practice that the initial form of the cap [5 maypreferably be formed cylindrical with its upwardly extending conicalsurface 18 and its lower inwardly extending conical surface 19substantially conforming,

, whereby to facilitate the conformation under high pressure of saidcap, IE to form the closure forthe head lfl'of the pintle 3,:in integralrela tion with the upper jaw member I.

My invention is advantageous in that, by censtructing the forceps orpliers in the manner herein specifically described, which includes theforming the pintle integral with one jaw mem- ,7

a r 4 when the plier beaks 5 and I are separated to assume an openposition.

I do not desire to limit my invention to the 'members, having theirouter surfaces convexed transversely, one having an aperture providedwith a recess affording a pivot engaging shoulder, and a counter recessproviding a circular undercut groove, the other having a relativelyalined aperture joining a conical recess having' indentations, a headedpintle extended through said alined apertures, having its head disposedin said first mentioned recess and engaging said shoulder, and havingits opposite end ,region expanded to conform to said conical recess andindentations, and a closure for said head engaging said groove andconforming to the curvature of theouter'surface of said implement.

2. An implement of the class described, com.- prising apair of opposedjaw members having their outer surfaces rounded transversely and beingrelatively movable about a common axis, a headed pintle extended throughalined apertures therein, one having a recess affording 'a retainingshoulder for relative rotation of the head of said pintle, and the otherhaving a tapered recess into which the opposite end region ofsaid'pintleis expanded into rigid non-rotating relation therewith, and a cover forthe head of 'saidpintle, conforming to the curvature of the outersurface of'said implement; and tightly expanded radially intonon-rotatable engagement with the walls of said recess, but rotatablewith respect to the head of said pintle. I I EDWARD BALDERSTONE-REFERENCES crrnir The following references are of record in the file ofth s p te t:

UNITED STATES PATENTS.

